The present invention relates to laser medical systems and, more particularly, to a medical radiation delivery arrangement which provides both desired flexibility and desired precision.
The output radiation of lasers now is widely used for treating various human and animal conditions. The nature of the delivery arrangement for the output laser radiation depends largely on the type of radiation to be delivered and the type of medical treatment or diagnostics. CO.sub.2 (carbon dioxide) laser radiation is used both internally and externally of a human body to create incisions. The principal component of CO.sub.2 radiation, e.g., 10.6 microns in wavelength, is in the infrared (IR) region of the electromagnetic spectrum and interacts favorably with tissue for surgery. However, methods and means which have been used in the past to deliver CO.sub.2 radiation to an operating site are not ideal. The conventional delivery means is via an articulated arm. An articulated arm basically is an arrangement of tubing, corner reflectors (mirrors) and movable joints. Such an arm generally is from one to one and one-half meters in length and has up to seven mirrors. The arm terminates at its output end in a handpiece or a micromanipulator. A handpiece often is used when the treatment site is external to the body, and is a simple lens for focusing the output energy to a small spot directly at the treatment site. A micromanipulator typically includes a joystick to aim the radiation through an endoscope to a treatment site at its remote end. (An endoscope, as used generically here, is basically a hollow tube to be inserted into a body cavity.) The use of a handpiece or a micromanipulator-endoscope, places the last position at which the beam is manipulated a significant distance away from the operating site. In a sense, this is like shining a light to a desired position at a far end of a pipe. That is, there is no guiding of the radiation--the surgeon must physically manipulate the beam at a distance to achieve the desired action at an operating site.
An articulated arm is sturdy and provides desired flexibility for delivering CO.sub.2 laser radiation. Because of its joints, such an arm enables a physician easily to vary the location to which output radiation is directed. This is a particularly important advantage during surgery. However, as discussed above, while an articulated arm provides desired flexibility, use of the same has not, until now, enabled the precise positioning that is necessary or desirable in many delicate operations.
Because of the problems mentioned above with articulated arms, some in the art have used optical waveguides, including fiberoptic and hollow air core waveguides, for the delivery of CO.sub.2 laser radiation for surgery or other medical treatment or diagnostic purposes. While guides of this nature generally are fragile and/or rigid, they do provide a precise and constant relationship between an output radiation beam guided to their output ends and the physical location of such output ends. Use of the same by surgeons has therefore been made to obtain the precision of delivery of radiation to a tissue site which is often needed. When optical waveguides are used, though, much of the flexibility associated with articulated arms is sacrificed. Hollow waveguides generally either are rigid or have very restricted bend radii. While the hollow waveguide described in the paper entitled "A Flexible CO.sub.2 Laser Fiber for Operative Laparoscopy" by Baggish, et al., published in the July 1986 issue of Fertility and Sterility is stated to be "flexible," it is a dielectrically coated metal (aluminum) tube having a restricted bend capability.
It should be noted that the desired flexibility cannot be regained simply by using an optical waveguide with a universally or articulated mounted laser. This does not provide the flexibility at the tissue site which is needed.
When the waveguide is a fiberoptic probe, flexing can result in internal breakage and corresponding attenuation of the output. Moreover, the length of infrared fiberoptic guides, the type of waveguide applicable for transmitting CO.sub.2 radiation, has been limited because of high infrared losses. The paper entitled "Medical Needs Drive IR Fiber Development" by one of the inventors hereof, James A. Harrington, appearing in the July 1987 issue of Photonics Spectra describes the various types of IR fibers and their limitations.